U.S. patent application number 12/481584 was filed with the patent office on 2010-02-25 for planar antenna and wireless communication apparatus.
This patent application is currently assigned to ASUSTeK COMPUTER INC.. Invention is credited to Hung-Hsiang Chen, Yang-Po Chiu, Ming-Iu Lai, Chun-Hsiung Wang.
Application Number | 20100045540 12/481584 |
Document ID | / |
Family ID | 41695871 |
Filed Date | 2010-02-25 |
United States Patent
Application |
20100045540 |
Kind Code |
A1 |
Lai; Ming-Iu ; et
al. |
February 25, 2010 |
PLANAR ANTENNA AND WIRELESS COMMUNICATION APPARATUS
Abstract
A planar antenna disposed on a plate having a first surface and
a second surface is provided. The planar antenna includes a metal
layer, an antenna body, a stepped impedance device, a coupling
device and a matching device. The metal layer is disposed on the
first surface and has a slot line exposing the first surface. The
antenna body, the stepped impedance device, the coupling device and
the matching device are disposed on the second surface. The antenna
body is corresponding to a surrounding of the metal layer except a
feed end thereof, the stepped impedance device and the matching
device are corresponding to the metal layer, and the coupling
device is corresponding to the slot line. The matching device is
coupled between the coupling device and the feed end. The stepped
impedance device has a transmission zero in a radio frequency band
operated by the antenna body.
Inventors: |
Lai; Ming-Iu; (Taipei,
TW) ; Chen; Hung-Hsiang; (Taipei, TW) ; Chiu;
Yang-Po; (Taipei, TW) ; Wang; Chun-Hsiung;
(Taipei, TW) |
Correspondence
Address: |
JIANQ CHYUN INTELLECTUAL PROPERTY OFFICE
7 FLOOR-1, NO. 100, ROOSEVELT ROAD, SECTION 2
TAIPEI
100
TW
|
Assignee: |
ASUSTeK COMPUTER INC.
Taipei
TW
|
Family ID: |
41695871 |
Appl. No.: |
12/481584 |
Filed: |
June 10, 2009 |
Current U.S.
Class: |
343/702 ;
343/860 |
Current CPC
Class: |
H01Q 1/48 20130101; H01Q
1/2266 20130101; H01Q 1/243 20130101; H01Q 9/0421 20130101 |
Class at
Publication: |
343/702 ;
343/860 |
International
Class: |
H01Q 1/50 20060101
H01Q001/50; H01Q 1/24 20060101 H01Q001/24 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 20, 2008 |
TW |
97131819 |
Claims
1. A planar antenna, disposed on a plate having a first surface and
a second surface, the planar antenna comprising: a metal layer,
disposed on the first surface, and having a slot line for exposing
the first surface; an antenna body, disposed on the second surface,
and having a ground end and a feed end, wherein the antenna body is
corresponding to a surrounding of the metal layer except a partial
area of the feed end thereof; a coupling device, disposed on the
second surface, and a partial area of the coupling device
corresponding to the slot line of the metal layer; a matching
device, disposed on the second surface in an approach of
corresponding to the metal layer, and electrically connected to the
coupling device and the feed end, wherein the matching device is
used for impedance matching between the antenna body and the
coupling device; and a stepped impedance device, disposed on the
second surface in the approach of corresponding to the metal layer,
and electrically connected to the ground end of the antenna body,
wherein the stepped impedance device has a transmission zero when
being operated in a radio frequency band.
2. The planar antenna as claimed in claim 1, wherein the radio
frequency band is used for transmitting a signal having a first
wavelength, and the stepped impedance device comprises: a first
impedance wire, having a first impedance Z.sub.1, and a distance
between two ends thereof being D.sub.1; and a second impedance
wire, having one end electrically connected to the first impedance
wire and another end electrically connected to the ground end of
the antenna body, and having a second impedance Z.sub.2, and a
distance between two ends thereof being D.sub.2, wherein when
.lamda..sub.1 is the first wavelength, .theta..sub.1 is a first
phase angle, and r is a positive number, the aforementioned
D.sub.1, D.sub.2, Z.sub.1 and Z.sub.2 are in accord with following
equations: tan
.theta..sub.1.times.tan(r.theta..sub.1)=Z.sub.1/Z.sub.2,
D.sub.1=(.theta..sub.1.times..lamda..sub.1)/360 and
D.sub.2=r.times.D.sub.1.
3. The planar antenna as claimed in claim 2, wherein the radio
frequency band is used for transmitting a signal having a second
wavelength, and the stepped impedance device further comprises: a
third impedance wire, having a third impedance Z.sub.3, and a
distance between two ends thereof being D.sub.3; and a fourth
impedance wire, having one end electrically connected to the third
impedance wire and another end electrically connected to the ground
end of the antenna body, and having a fourth impedance Z.sub.4, and
a distance between two ends thereof being D.sub.4, wherein when
.lamda..sub.2 is the second wavelength, .theta..sub.2 is a second
phase angle, and s is a positive number, the aforementioned
D.sub.3, D.sub.4, Z.sub.3 and Z.sub.4 are in accord with following
equations: tan
.theta..sub.2.times.tan(s.theta..sub.2)=Z.sub.3/Z.sub.4,
D.sub.3=(.theta..sub.2.times..lamda..sub.2)/360 and
D.sub.4=s.times.D.sub.3.
4. The planar antenna as claimed in claim 1, wherein the coupling
device comprises: a first coupling wire, having nonadjacent a first
side and a second side, wherein the first side is electrically
connected to the feed end of the antenna body, and a position of
the first coupling wire is corresponding to the slot line; and a
second coupling wire, electrically connected to the second side of
the first coupling wire.
5. The planar antenna as claimed in claim 4, wherein a shape of the
first coupling wire is a rectangle or a trapezoid.
6. The planar antenna as claimed in claim 4, wherein a shape of the
second coupling wire is a rectangle or a trapezoid.
7. The planar antenna as claimed in claim 1, wherein the slot line
comprises: a linear opening, penetrating the metal layer for
exposing the first surface.
8. The planar antenna as claimed in claim 7, wherein the slot line
further comprises: a first opening, penetrating the metal layer,
and communicated to a side of the linear opening; and a second
opening, penetrating the metal layer, and communicated to another
side of the linear opening.
9. The planar antenna as claimed in claim 8, wherein shapes of the
first opening and the second opening are rounds or triangles.
10. The planar antenna as claimed in claim 1 further comprising: a
coaxial wire, having an inner conductor and an outer conductor,
wherein the outer conductor is electrically connected to the metal
layer, and the inner conductor is electrically connected to the
metal layer by crossing the slot line.
11. The planar antenna as claimed in claim 1, wherein the antenna
body is an inverted-F antenna body.
12. The planar antenna as claimed in claim 1, wherein the plate is
a printed circuit board.
13. A wireless communication apparatus, comprising: a first plate,
having a first surface and a second surface; a second plate, the
first plate and the second plate forming a chamber to contain an
inner circuit of the wireless communication apparatus; and a
plurality of planar antennas, disposed on the first plate, and each
of the planar antennas comprising: a metal layer, disposed on the
first surface, and having a slot line for exposing the first
surface; an antenna body, disposed on the second surface, and
having a ground end and a feed end, wherein the antenna body is
corresponding to a surrounding of the metal layer except a partial
area of the feed end thereof; a coupling device, disposed on the
second surface, and a partial area of the coupling device
corresponding to the slot line of the metal layer; a matching
device, disposed on the second surface in an approach of
corresponding to the metal layer, and electrically connected to the
coupling device and the feed end of the antenna body, wherein the
matching device is used for impedance matching between the antenna
body and the coupling device; and a stepped impedance device,
disposed on the second surface in the approach of corresponding to
the metal layer, and electrically connected to the ground end of
the antenna body, wherein the stepped impedance device has a
transmission zero when being operated in a radio frequency
band.
14. The wireless communication apparatus as claimed in claim 13,
wherein the first surface is a part of inner wall of the
chamber.
15. The wireless communication apparatus as claimed in claim 14
further comprising: a display panel, disposed in the chamber, and a
position thereof is fixed between the metal layer and a transparent
block of the second plate.
16. The wireless communication apparatus as claimed in claim 13
further comprising: an insulation layer, covering the antenna body,
the stepped impedance device and the coupling device.
17. The wireless communication apparatus as claimed in claim 13,
wherein the radio frequency band is used for transmitting a signal
having a first wavelength, and the stepped impedance device
comprises: a first impedance wire, having a first impedance
Z.sub.1, and a distance between two ends thereof being D.sub.1; and
a second impedance wire, having one end electrically connected to
the first impedance wire and another end electrically connected to
the ground end of the antenna body, and having a second impedance
Z.sub.2, and a distance between two ends thereof being D.sub.2,
wherein when .lamda..sub.1 is the first wavelength, .theta..sub.1
is a first phase angle, and r is a positive number, the
aforementioned D.sub.1, D.sub.2, Z.sub.1 and Z.sub.2 are in accord
with following equations: tan
.theta..sub.1.times.tan(r.theta..sub.1)=Z.sub.1/Z.sub.2,
D.sub.1=(.theta..sub.1.times..lamda..sub.1)/360 and
D.sub.2=r.times.D.sub.1.
18. The wireless communication apparatus as claimed in claim 13,
wherein the coupling device comprises: a first coupling wire,
having nonadjacent a first side and a second side, wherein the
first side is electrically connected to the feed end of the antenna
body, and a position of the first coupling wire is corresponding to
the slot line; and a second coupling wire, electrically connected
to the second side of the first coupling wire.
19. The wireless communication apparatus as claimed in claim 13,
wherein the slot line comprises: a linear opening, penetrating the
metal layer for exposing the first surface.
20. The wireless communication apparatus as claimed in claim 13,
wherein the slot line further comprises: a first opening,
penetrating the metal layer, and communicated to a side of the
linear opening; and a second opening, penetrating the metal layer,
and communicated to another side of the linear opening.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the priority benefit of Taiwan
application serial no. 97131819, filed Aug. 20, 2008. The entirety
of the above-mentioned patent application is hereby incorporated by
reference herein and made a part of specification.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a planar antenna and a
wireless communication apparatus. More particularly, the present
invention relates to a planar antenna without a through-hole
structure and a wireless communication apparatus
[0004] 2. Description of Related Art
[0005] With development of hardware device and technique for
wireless transmission, a multi input multi output (MIMO) technique
has become an important indicator for a high efficiency wireless
communication technique, and gradually becomes a main stream for
future wireless communication. Different to a conventional design
of a single antenna, the MIMO technique applies multi antennas to
achieve multi-path transmission of a wireless network. Moreover,
the MIMO technique has advantages of improving a transmission speed
and a signal-receiving range of the wireless network, etc.
[0006] In the wireless network mainly applying the MIMO technique,
the wireless communication apparatus has to apply a plurality of
antennas to implement the multi-path transmission mechanism. For
example, assuming a wireless local area network (WLAN) applies a
3.times.3 MIMO system, and a worldwide interoperability for
microwave access (WiMAX) applies a 2.times.2 MIMO system, the
wireless communication apparatus then has to utilize 5 antennas for
being applied to the WLAN and WiMAX.
[0007] However, a cost of a single antenna is about 20-30 NT
presently, so that 100-150 NT have to be spent for the antenna cost
of the wireless communication apparatus. Moreover, as a number of
the inbuilt antenna increases, a system manufacture has to spend
more human labours and time for assembling the antennas. In other
words, when a plurality of antenna is applied to the wireless
communication apparatus, the antenna size, the material cost and
the labour cost for assembling are greatly increased.
SUMMARY OF THE INVENTION
[0008] The present invention is directed to a planar antenna, which
can apply a stepped impedance device to substitute a through-hole
structure, and can be directly printed on a plate.
[0009] The present invention is directed to a wireless
communication apparatus, in which a material cost and a labour cost
for assembling is not greatly increased as a number of inbuilt
planar antennas increases.
[0010] The present invention provides a planar antenna disposed on
a plate, wherein the plate has a first surface and a second
surface. The planar antenna includes a metal layer, an antenna
body, a stepped impedance device, a coupling device and a matching
device. The metal layer is disposed on the first surface and has a
slot line for exposing the first surface.
[0011] The antenna body is disposed on the second surface, and has
a ground end and a feed end. Moreover, the antenna body is
corresponding to a surrounding of the metal layer except a partial
area of the feed end thereof The coupling device is disposed on the
second surface, and a partial area of the coupling device is
corresponding to the slot line of the metal layer. The matching
device is disposed on the second surface in an approach of
corresponding to the metal layer, and is electrically connected to
the coupling device and the feed end. Wherein, the matching device
is used for impedance matching between the antenna body and the
coupling device. In addition, the stepped impedance device is
disposed on the second surface in an approach of corresponding to
the metal layer, and is electrically connected to the ground end of
the antenna body.
[0012] On the other hand, in a whole operation, when the stepped
impedance device is operated in a radio frequency band, it can have
a transmission zero and is regarded as an open circuit.
Accordingly, the antenna body can generate a resonance mode in such
radio frequency band, and can receive or emit signals of such radio
frequency band. Moreover, the signal received by the antenna body
can be coupled to a lead wire crossing the slot line through the
coupling device.
[0013] In an embodiment of the present invention, the radio
frequency band is used for transmitting a signal having a first
wavelength, and the stepped impedance device includes a first
impedance wire and a second impedance wire. Wherein, the first
impedance wire has a first impedance Z.sub.1, and a distance
between two ends thereof is D.sub.1. The second impedance wire has
a second impedance Z.sub.2, and a distance between two ends thereof
is D.sub.2. Moreover, one end of the second impedance wire is
electrically connected to the first impedance wire, and another end
of the second impedance wire is electrically connected to the
ground end of the antenna body.
[0014] It should be noted that when .lamda..sub.1 is the first
wavelength, .theta..sub.1 is a first phase angle, and r is a
positive number, the aforementioned D.sub.1, D.sub.2, Z.sub.1 and
Z.sub.2 are in accord with following equations: tan
.theta..sub.1.times.tan(r.theta..sub.1)=Z.sub.1/Z.sub.2,
D.sub.1=(.theta..sub.1.times..lamda..sub.1)/360 and
D.sub.2=r.times.D.sub.1.
[0015] In an embodiment of the present invention, the coupling
device includes a first coupling wire and a second coupling wire.
Wherein, the first coupling wire is directly or indirectly
connected to the feed end of the antenna body, electrically, and a
position of the first coupling wire is corresponding to the slot
line. Moreover, the second coupling wire is electrically connected
to the first coupling wire.
[0016] In an embodiment of the present invention, the slot line
includes a linear opening, a first opening and a second opening.
Wherein, the linear opening, the first opening and the second
opening penetrate the metal layer to expose the first surface.
Moreover, the first opening is communicated to a side of the linear
opening, and the second opening is communicated to another side of
the linear opening.
[0017] The present invention further provides a wireless
communication apparatus including a first plate, a second plate and
a plurality of planar antennas, wherein the first plate has a first
surface and a second surface. The second plate and the first plate
form a chamber to contain an inner circuit of the wireless
communication apparatus. Moreover, the planar antennas are all
disposed on the first plate, and a structure of each of the planar
antennas is the same to that of the aforementioned planar
antenna.
[0018] In an embodiment of the present invention, the first surface
is a part of inner wall of the chamber. Moreover, the wireless
communication apparatus further includes a display panel and an
insulation layer, wherein the display panel is disposed in the
chamber, and a position thereof is fixed between the metal layer
and a transparent block of the second plate. The insulation layer
covers the antenna body, the stepped impedance device and the
coupling device.
[0019] In the present invention, the stepped impedance device is
used for substituting a through-hole structure in a conventional
planar antenna. Moreover, the coupling device is used for coupling
the signal received by the planar antenna to the lead wire crossing
the slot line of the metal layer. Therefore, compared to the
conventional technique, the planar antenna of the present invention
can be directly printed on the plate, so that a material cost and a
labour cost for assembling can be effectively reduced.
Comparatively, the wireless communication apparatus can implement
the multi-path transmission mechanism by applying the planar
antenna of the present invention, so as to restrain a great
increase of the material cost and the labour cost for
assembling.
[0020] In order to make the aforementioned and other objects,
features and advantages of the present invention comprehensible, a
preferred embodiment accompanied with figures is described in
detail below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The accompanying drawings are included to provide a further
understanding of the invention, and are incorporated in and
constitute a part of this specification. The drawings illustrate
embodiments of the invention and, together with the description,
serve to explain the principles of the invention.
[0022] FIG. 1 is a schematic diagram illustrating a structure of a
planar antenna according to an embodiment of the present
invention.
[0023] FIG. 2 is a diagram illustrating a configuration of a
coaxial wire 210 on a plate 101.
[0024] FIG. 3 is a cross-sectional view of FIG. 2 cut along a A-A'
line.
[0025] FIG. 4 is a partial amplified diagram of the embodiment of
FIG. 1.
[0026] FIG. 5 is a curve diagram corresponding to an equation
(1).
[0027] FIG. 6 is a schematic diagram illustrating a structure of an
antenna body and a stepped impedance device according to another
embodiment of the present invention.
[0028] FIG. 7A is another partial amplified diagram of the
embodiment of FIG. 1.
[0029] FIG. 7B is a schematic diagram illustrating a structure of a
coupling device according to another embodiment of the present
invention.
[0030] FIG. 8A is another partial amplified diagram of the
embodiment of FIG. 1.
[0031] FIG. 8B is a schematic diagram illustrating a structure of a
slot line according to another embodiment of the present
invention.
[0032] FIG. 9A is a curve diagram illustrating coupling frequencies
of a coupling device according to an embodiment of the present
invention.
[0033] FIG. 9B is a curve diagram illustrating coupling frequencies
of a coupling device according to another embodiment of the present
invention.
[0034] FIG. 10 is an exploded perspective view of a wireless
communication apparatus according to an embodiment of the present
invention.
[0035] FIG. 11 is a cross-sectional view of a wireless
communication apparatus 900 of FIG. 10 cut along a B-B' line.
DESCRIPTION OF EMBODIMENTS
[0036] FIG. 1 is a schematic diagram illustrating a structure of a
planar antenna according to an embodiment of the present invention.
The planar antenna 100 is disposed on a plate 101, and the plate
101 has a first surface 101a and a second surface 101b.
[0037] It should be noted that in the present embodiment, the plate
101 can be a printed circuit board (PCB), and the first surface
101a is parallel to the second surface 101b. However, those skilled
in the art can also apply the planar antenna 100 to any plate
having two surfaces according to actual design requirements. In
other words, though the present embodiment provides a possible
pattern of the plate 101, it is not used for limiting the present
invention.
[0038] Referring to FIG. 1 again, the planar antenna 100 includes a
metal layer 110, an antenna body 120, a stepped impedance device
130, a coupling device 140 and a matching device 150. Wherein, the
metal layer 110 is disposed on the first surface 101a and has a
slot line 111 for exposing the first surface 101a. On the other
hand, the antenna body 120, the stepped impedance device 130, the
coupling device 140 and the matching device 150 are all disposed on
the second surface 101b according to a position of the metal layer
110.
[0039] For simplicity's sake, a corresponding position of the metal
layer 110 on the second surface 101b is illustrated by dash lines.
Referring to FIG. 1, the antenna body 120 is disposed on the second
surface 101b, and has a ground end 121 and a feed end 122. It
should be noted that except a partial area of the feed end 122, the
antenna body 120 is disposed on the second surface 101b in an
approach of corresponding to a surrounding of the metal layer 110.
Moreover, the stepped impedance device 130 is disposed on the
second surface 101b in an approach of corresponding to the metal
layer 110, and is electrically connected to the ground end 121 of
the antenna body 120.
[0040] Moreover, the coupling device 140 is disposed on the second
surface 101b, and a partial area of the coupling device 140 is
disposed on the second surface 101b in an approach of corresponding
to the slot line 111 of the metal layer 110. On the other hand, the
matching device 150 is disposed on the second surface 101b in an
approach of corresponding to the metal layer 110, and is
electrically connected to the coupling device 140 and the feed end
122 of the antenna body 120. Here, the matching device 150 is used
for impedance matching between the antenna body 120 and the
coupling device 140.
[0041] In a whole operation, when the stepped impedance device 130
is operated in a certain radio frequency band, it can generate a
transmission zero and is regarded as an open circuit. Accordingly,
the antenna body 120 can generate a resonance mode in the
above-mentioned radio frequency band, and can receive or emit
signals in the above-mentioned radio frequency band. Moreover, the
signal received by the antenna body 120 can be guided to a coaxial
wire through the coupling device 140.
[0042] For example, the planar antenna 100 further includes a
coaxial wire 210. FIG. 2 is a diagram illustrating a configuration
of the coaxial wire 210 on the plate 101, and FIG. 3 is a
cross-sectional view of FIG. 2 along a A-A' line. Referring to FIG.
2 and FIG. 3, if the signal received by the antenna body 120 is
transmitted through the coaxial wire 210, an outer conductor 212 of
the coaxial wire 210 is electrically connected to the metal layer
110, and an inner conductor 211 of the coaxial wire 210 is
electrically connected to the metal layer 110 by crossing the slot
line 111. Therefore, the signal received by the antenna body 120
can be transmitted to the coupling device 140 through the feed end
122 and the matching device 150, and is conducted to the coaxial
wire 210 through the coupling device 140.
[0043] It should be noted that the planar antenna 100 can be
directly printed on the plate 101 according to any printing
technique. During an actual fabrication process, the stepped
impedance device 130 of the planar antenna 100 substitutes a
through-hole structure of a conventional planar antenna. Therefore,
a material cost the planar antenna 100 and a labour cost for
assembling the planar antenna 100 can be effectively reduced.
[0044] FIG. 4 is a partial amplified diagram of the embodiment of
FIG. 1. Referring to FIG. 4 to study the antenna body 120 and the
stepped impedance device 140 of FIG. 1 in detail. Here, the antenna
body 120 is an inverted-F antenna body operated in a single
frequency. Namely, a radio frequency band in which the antenna body
120 is operated is used for transmitting signals of a single
wavelength.
[0045] Here, the antenna body 120 is composed of the ground end
121, the feed end 122 and a excitation part 123. The ground end 121
is electrically connected to one end of the excitation part 123.
The feed end 122 is electrically connected between two ends of the
excitation part 123. An intersection position of the feed end 122
and the excitation part 123 is determined according to a position
between an open end of the excitation part 123 and the ground end
121 that can cause a minimum reflection. Moreover, a length D41
between two ends of the excitation part 123 is closed to a
wavelength of the single-frequency signal transmitted by the
antenna body 120.
[0046] Referring to FIG. 4 again, in the present embodiment, the
stepped impedance device 130 is composed of impedance wires 131 and
132. One end of the impedance wire 132 is electrically connected to
the ground end 121 of the antenna body 120, and another end of the
impedance wire 132 is electrically connected to the impedance wire
131. Regarding a whole operation, to ensure the stepped impedance
device 130 generating the transmission zero in the single frequency
operated by the antenna body 130, sizes of the impedance wires 131
and 132 have to be in accord with following mathematic
equations.
[0047] Here, distances between two ends of the impedance wires 131
and 132 are D.sub.1 and D.sub.2 respectively, and impedances of the
impedance wires 131 and 132 are Z.sub.1 and Z.sub.2 respectively.
Wherein, if the operation radio frequency band of the antenna body
120 is used for transmitting the signal with a wavelength of
.lamda.1, r is a positive number and .THETA..sub.1 is a phase
angle, the mathematic equations (1)-(3) used for determine the
sizes of the impedance wires 131 and 132 are as follows:
tan .theta. 1 .times. tan ( r .theta. 1 ) = Z 1 Z 2 ( 1 ) D 1 =
.theta. 1 .times. .lamda. 1 360 ( 2 ) D 2 = ( r .theta. 1 ) .times.
.lamda. 1 360 = r .times. D 1 ( 3 ) ##EQU00001##
[0048] If represented by a figure, the mathematic equation (1) is
then shown as FIG. 5, wherein an X axis thereof is the phase angles
.THETA..sub.1, and a Y axis is ratios R.sub.Z between the
impedances Z.sub.1 and Z.sub.2. Referring to FIG. 5, when r=1,
relations between the phase angles .THETA..sub.1 and the ratios
R.sub.Z are shown as a curve 510. Comparatively, when r=1.2,
relations between the phase angles .THETA..sub.1 and the ratios
R.sub.Z are shown as a curve 520. Accordingly, relative relations
between curves 530-550 and the value r can be deduced by analogy.
Here, a designer can easily design a suitable stepped impedance
device 130 according to FIG. 5.
[0049] It should be noted that though the inverted-F antenna body
120 operated in the single frequency is taken as an example, in an
actual application, the antenna body 120 can also be substituted by
an inverted-F antenna body 120' operated in a dual-frequency, as
that shown in FIG. 6.
[0050] FIG. 6 is a schematic diagram illustrating a structure of an
antenna body and a stepped impedance device according to another
embodiment of the present invention. Referring to FIG. 6, when the
antenna body 120 is substituted by the inverted-F antenna body 120'
operated in the dual-frequency, the operation radio frequency band
of the antenna body 120' is not only used for transmitting the
signal with the wavelength of .lamda..sub.1, but is also used for
transmitting the signal with a wavelength of .lamda..sub.2, wherein
.lamda..sub.1.noteq..lamda..sub.2, Comparatively, the stepped
impedance device 130 that can generate the transmission zero in the
single frequency is substituted by a stepped impedance device 130'
that can generate the transmission zero in the dual frequency.
[0051] Here, the stepped impedance device 130' not only includes
the impedance wires 131 and 132 designed according to the
wavelength .lamda..sub.1, but also includes the impedance wires 133
and 133 designed according to the wavelength .lamda..sub.2.
Wherein, one end of the impedance wire 134 is electrically
connected to a ground terminal 121' of the antenna body 120', and
another end of the impedance wire 134 is electrically connected to
the impedance wire 133. In the whole operation, to ensure the
stepped impedance device 130 generating the transmission zero in
another frequency, sizes of the impedance wires 133 and 134 have to
be in accord with following mathematic equations.
[0052] Here, distances between two ends of the impedance wires 133
and 134 are D.sub.3 and D.sub.4 respectively, and impedances of the
impedance wires 133 and 134 are Z.sub.3 and Z.sub.4 respectively.
Wherein, if s is another positive number and .THETA..sub.2 is
another phase angle, the mathematic equations (4)-(6) used for
determine the sizes of the impedance wires 133 and 134 are as
follows:
tan .theta. 2 .times. tan ( s .theta. 2 ) = Z 3 Z 4 ( 4 ) D 3 =
.theta. 2 .times. .lamda. 2 360 ( 5 ) D 4 = ( s .theta. 2 ) .times.
.lamda. 2 360 = s .times. D 3 ( 6 ) ##EQU00002##
[0053] Wherein, those skilled in the art can illustrate the
equation (4) into a waveform diagram illustrating relations between
ratios of the impedances Z.sub.3 and Z.sub.4 and the phase angles
.THETA..sub.2 while referring to FIG. 5.
[0054] FIG. 7A is another partial amplified diagram of the
embodiment of FIG. 1. Referring to FIG. 7A, the coupling device 140
of FIG. 1 is further studied. In the present embodiment, the
coupling device 140 includes coupling wires 710 and 720. Wherein,
the coupling wire 710 has nonadjacent a first side and a second
side. Here, the first side of the coupling wire 710 is electrically
connected to the matching device 150, and the second side of the
coupling wire 710 is electrically connected to the coupling wire
720.
[0055] Regarding a whole configuration, a position of the coupling
wire 710 is corresponding to the slot line 111 (shown as the dash
lines in FIG. 7A). Moreover, in the present embodiment, shapes of
the coupling wires 710 and 720 are rectangles. However, in an
actual application, the shapes of the coupling wires 710 and 720
can be varied. FIG. 7B is a schematic diagram illustrating a
structure of a coupling device according to another embodiment of
the present invention. As shown in FIG. 7B, the rectangular
coupling wire 710 is changed to be a trapezoid coupling wire 710'.
In other words, during the actual design, as long as the position
of the coupling wire 710 is corresponding to the slot line 111, the
shape of the coupling wire can be arbitrarily changed.
[0056] FIG. 8A is another partial amplified diagram of the
embodiment of FIG. 1. Referring to FIG. 8A, the slot line 111 of
FIG. 1 is further studied. In the present embodiment, the slot line
111 is composed of a linear opening 810. Wherein, the linear
opening 810 penetrates the metal layer 110 and exposes the first
surface 101a. However, during the actual application, a shape of
the opening can be varied. FIG. 8B is a schematic diagram
illustrating a structure of a slot line according to another
embodiment of the present invention. As shown in FIG. 8B, the slot
line 111 can be composed of the linear opening 810 and different
shape of openings.
[0057] For example, in FIG. 8B, the slot line 111 includes a linear
opening 810, and openings 820 and 830. Here, the linear opening
810, the openings 820 and 830 all penetrate the metal layer 110 to
expose the first surface 101a. Moreover, the opening 820 is
communicated to one side of the linear opening 810, and the opening
830 is communicated to another side of the linear opening 810. It
should be noted that in the present embodiment, shapes of the
openings 820 and 830 are rounds, and the slot line 111 is
dumbbell-shaped. However, in the actual application, the shapes of
the openings 820 and 830 can also be triangles. In other words, the
shapes of the openings 820 and 830 can be arbitrarily changed
according to actual design requirements.
[0058] It should be noted that a coupling frequency of the coupling
device 140 is mainly determined according to the sizes and shapes
of the coupling device 140 and the slot line 111, and a main reason
thereof is as follows. Referring to FIG. 3, during a process when
the signal received by the antenna body 120 is guided to the
coaxial wire 210 through the coupling device 140 and the slot line
111, the coupling device 140 and the metal layer 110 can form an
equivalent capacitor, and the inner conductor 211 crossing the slot
line 111 is regarded as an equivalent inductor. Here, resistances
of the equivalent capacitor and the equivalent inductor are
determined according to the sizes and shapes of the coupling device
140 and the slot line 111.
[0059] Moreover, FIG. 9A and FIG. 9B are curve diagrams
respectively illustrating coupling frequencies of a coupling device
according to an embodiment of the present invention. Wherein, when
the coupling device 140 of FIG. 7A is used together with the
rectangular slot line 111 (shown in FIG. 8A), as shown in FIG. 9A,
the coupling frequency of the coupling device 140 is between 2-3
GHz. Now, the coupling device 140 is adapted to a narrowband
design. For example, the coupling device 140 can be applied to a
WLAN within 2.4 GHz frequency band or a WiMAX within 2-3 GHz
frequency band.
[0060] Moreover, when the coupling device 140 of FIG. 7B is used
together with the trapezoid slot line 111 (shown in FIG. 8B), as
shown in FIG. 9B, the coupling frequency of the coupling device 140
is between 2-6 GHz. Now, the coupling device 140 is adapted to a
broadband design. For example, the coupling device 140 can be
applied to a WLAN and a WiMAX within 2.4 GHz and 5.0 GHz frequency
band.
[0061] FIG. 10 is an exploded perspective view of a wireless
communication apparatus according to an embodiment of the present
invention. Referring to FIG. 10, the wireless communication
apparatus 900 includes a plate 910, a plate 920 and a plurality of
planar antennas (for example, planar antennas 930). Wherein,
structures of the planar antennas are the same to that of the
planar antenna 100 of FIG. 1. For simplicity's sake, the planar
antenna 930 is taken as an example. Moreover, an inside view of an
area A of the plate 910 is further illustrated in FIG. 10.
[0062] FIG. 11 is a cross-sectional view of the wireless
communication apparatus 900 of FIG. 10 cut along a B-B' line.
Referring to FIG. 10 and FIG. 11, the plate 920 has a first surface
911 and a second surface 912. Moreover, the plate 920 is overlapped
to the plate 910 to form a chamber to contain an inner circuit of
the wireless communication apparatus 900. In other words, during
the actual application, the plates 910 and 920 function as a
housing of the wireless communication apparatus 900, and the planar
antenna 930 is disposed on the housing of the wireless
communication apparatus 900.
[0063] Further, the planar antenna 930 is disposed on the plate
910, and includes a metal layer 931, an antenna body 932, a stepped
impedance device 933, a coupling device 934 and a matching device
935. Wherein, the metal layer 931 is disposed on the first surface
911, and a corresponding position thereof on the second surface 912
is shown as the dash lines. Moreover, the metal layer 931 has a
slot line 950 for exposing the first surface 911.
[0064] In addition, the antenna body 932 has a ground end 961 and a
feed end 962 disposed on the second surface 912. Moreover, the
antenna body 932 is corresponding to a surrounding of the metal
layer 931 except a partial area of the feed end 962 thereof The
stepped impedance device 933 is disposed on the second surface 912
in an approach of corresponding to the metal layer 931, and is
electrically connected to the ground end 961 of the antenna body
932.
[0065] Moreover, the coupling device 934 is disposed on the second
surface 912, and a partial area of the coupling device 934 is
disposed on the second surface 912 in an approach of corresponding
to the slot line 950 of the metal layer 931. In addition, the
matching device 935 is disposed on the second surface 912 in an
approach of corresponding to the metal layer 931, and is
electrically connected to the coupling device 934 and the feed end
962 of the antenna body 932. Wherein, the matching device 935 is
used for impedance matching between the antenna body 932 and the
coupling device 934.
[0066] In a whole operation, when the stepped impedance device 933
is operated in a certain radio frequency band, it can have a
transmission zero and is regarded as an open circuit. Accordingly,
the antenna body 932 can generate a resonance mode in such radio
frequency band, and can receive or emit signals of such radio
frequency band. Moreover, the signal received by the antenna body
932 can be guided to a coaxial wire (for example, a coaxial wire
970) through the coupling device 934 and the slot line 950. By such
means, the inner circuit of the wireless communication apparatus
900 can receives signals from the antenna body 932 through the
coaxial wire.
[0067] Detail structures of the devices within the planar antenna
930, for example, types, shapes and patterns, etc. of the antenna
body 932, the stepped impedance device 933 and the coupling device
934 have been described in the aforementioned embodiments, and
therefore detailed descriptions thereof are not repeated.
[0068] It should be noted that the wireless communication apparatus
900 further includes a display panel 980 and an insulation layer
990. The first surface 911 of the plate 910 is a part of inner wall
of the chamber 940. Moreover, the display panel 980 is disposed in
the chamber 940, and is fixed between the metal layer 931 and a
transparent block 921 of the plate 920. By such means, the metal
layer 931 can suppress an electromagnetic interference. On the
other hand, the insulation layer 990 covers the antenna body 932,
the stepped impedance device 933, the coupling device 934 and the
matching device 935, so as to prevent the planar antenna 930 from
damaging during utilization of the wireless communication apparatus
900.
[0069] In summary, the stepped impedance device of the present
invention is used for substituting a through-hole structure in a
conventional planar antenna, and the coupling device is used for
coupling the signal received by the planar antenna to the lead wire
crossing the slot line of the metal layer. Therefore, the planar
antenna of the present invention can be directly printed on the
plate, so that a material cost of the planar antenna and a labour
cost for assembling the planar antenna can be effectively reduced.
Comparatively, when the planar antenna of the present invention is
applied to the wireless communication apparatus, the material cost
of the wireless communication apparatus and the labour cost for
assembling the same are not great increased as a number of the
inbuilt antennas is increased.
[0070] It will be apparent to those skilled in the art that various
modifications and variations can be made to the structure of the
present invention without departing from the scope or spirit of the
invention. In view of the foregoing, it is intended that the
present invention cover modifications and variations of this
invention provided they fall within the scope of the following
claims and their equivalents.
* * * * *